Abstract [en]

Formation of elongated nanoparticles was observed when FE3O4 was precipitated from solutions containing excess of Fe2+. The average diameter of the particles was 23 nm; the length to diameter ratio was up to 14. This shape was an unexpected phenomenon because bar- or needle-like nanoparticles have been earlier reported only for Fe(III)-based materials. Chemical analysis revealed Fe(OH)(2) nature of the obtained particles. In addition, this conclusion was verified with a new simple method for quantitative evaluation of the particle morphology. Application of this method to the mixed Fe(OH)(2/)Fe3O4 samples allowed to distinguish between the two different compounds and to attribute different morphologies to Fe(OH)(2) or Fe3O4. Results indicate that bars are frequent shapes of nano-sized iron oxides/hydroxides.